Same Tree

Problem Summary

• Given two roots of trees, return whether they are the same

What is Being Asked?

• Traverse through both trees and check whether they are the same

Main Concepts Used

• Trees
• Pre-order Traversal

Time & Space Complexity

• Time: $O(n)$ → Reason: Need to visit each node from both trees.
• Space: $O(n)$ → Reason: Recursive call stack of the height of the tree which could be $n$ in a skewed tree

Code

class Solution:
    def isSameTree(self, p: Optional[TreeNode], q: Optional[TreeNode]) -> bool:
        if not p and not q:
            return True

        if not p or not q:
            return False

        # at this point, we know for sure both nodes exist
        if p.val != q.val:
            return False

        return self.isSameTree(p.left, q.left) and self.isSameTree(p.right, q.right)